Thanks Alan. The whole issue hit home with me this week when I was talking to my kids about planets and my five-year-old daughter corrected me and and said "Pluto is not a planet. My teacher told me that." I'll be glad to see the discussion opened up again in a serious forum.

Forgive the, perhaps ignorant question... but do the people at this coming debate have the authority to change the status of Pluto? i.e. change what objects are planets, and what objects are dwarf planets? I'm guessing "No.", but am not sure.

But they can try and come up with a better way of categorizing them - the current system is utterly broken (and that's coming from someone who doesn't care if Pluto is a planet or not,I just want a definition that makes sense)

But they can try and come up with a better way of categorizing them - the current system is utterly broken (and that's coming from someone who doesn't care if Pluto is a planet or not,I just want a definition that makes sense)

He says he personally considers the debate closed, but since we don't seem to be able to move on, he proposes some rules for the discussion.

There's a lot of good stuff here, but this struck me as new information:

QUOTE

Misleading statements about the previous vote should also be disallowed. Yes, the whole IAU procedure was a bit mucked up, but the results would likely have been the same no matter who was in the room at the time. Surveys done after the IAU vote – yes there were some! – showed that astronomers by a large number thought that the 8 planets definition was a good one. So complaining about the IAU vote gets you the label of “misinformed about how most astronomers think."

I thought that was a particularly strong claim. I wonder who does those surveys? :-)

I'd sure like to know too. The only one I know of is the Sykes-Stern petition, which in 48 hours after being introduced gained 300+ signatories who were displeased with the IAU vote.

Brown's assertion that the vote "would" have been the same is unsupported.

Worse, voting in science is about the worst way one can go: can you imagine if there were voting on evolution, global change, etc.? Voting is antithetical to science, which works by archieving consensus based on which models best fit an ever expanding base of data.

Anyway, The GPD later this week in Maryland will feature debate and no votes. Come to the meeting or tune in if you can't and are interested.

It reminds me of how Stephen Colbert decides whether an idea is right or wrong based on how well it sells. For example, he changed positions on global warming because Al Gore's book sold more copies than those written to oppose his position (for those outside the U.S., the Colbert Report is a parody news program).

Worse, voting in science is about the worst way one can go: can you imagine if there were voting on evolution, global change, etc.? Voting is antithetical to science, which works by archieving consensus based on which models best fit an ever expanding base of data.

I agree. However, in this case the debate is over terminology, not science. In my own opinion (for what it is worth), the term 'planet' is obsolete and should be retired. I would go with several sets of terms for each type of object: a set of terms for composition -- 'gas giant', 'ice giant', 'terrestrial' and 'ice dwarf'; a set of terms for orbital status -- orbiting the Sun, orbiting another body that in turn orbits the Sun, or in a mean-motion resonance with a more massive Sun-orbiting body; and a set of terms for gravitational self-rounding (including non-typical objects like 2003 EL61) -- fully gravitationally relaxed, partially relaxed, unrelaxed.

So Pluto would be a fully gravitationally relaxed ice dwarf in a mean-motion resonance with a more massive Sun-orbiting object.

Luna would be a fully gravitationally relaxed terrestrial orbiting a more massive Sun-orbiting object.

Vesta would be a partially gravitationally relaxed terrestrial orbiting the Sun.

I agree. However, in this case the debate is over terminology, not science. In my own opinion (for what it is worth), the term 'planet' is obsolete and should be retired. I would go with several sets of terms for each type of object: a set of terms for composition -- 'gas giant', 'ice giant', 'terrestrial' and 'ice dwarf'; a set of terms for orbital status -- orbiting the Sun, orbiting another body that in turn orbits the Sun, or in a mean-motion resonance with a more massive Sun-orbiting body; and a set of terms for gravitational self-rounding (including non-typical objects like 2003 EL61) -- fully gravitationally relaxed, partially relaxed, unrelaxed.

So Pluto would be a fully gravitationally relaxed ice dwarf in a mean-motion resonance with a more massive Sun-orbiting object.

Luna would be a fully gravitationally relaxed terrestrial orbiting a more massive Sun-orbiting object.

Vesta would be a partially gravitationally relaxed terrestrial orbiting the Sun.

And so on.

Mongo-

Since planetary science is a field and planetary scientists have a profession, I do not think we can or want to retire the term which planets. Instead, our field and our profession need to come to a consensus on what we, the practitioners, consider to be planets vs. smaller and vs. larger things. That astronomers hijacked this process is about equivalent to brain surgeons, rather than cardiologists, deciding where the dividing lines between veins, arteries, and capillaries are, and the public/press following along because "they are all doctors, after all."

As to Hungry4Info's question, no one really has the authority to change the status of Pluto or other bodies. Science doesn't work by such decrees-- it works by finding the best solution that fits the data, which is fundamentally about achieving consensus, not votes or decrees.

To register for Great Planet Debate conference web participation, click: http://tinyurl.com/6xcqecWatch the talks and debate on line!

-Alan

Are we able to participate in the conference as a whole, then? I have registered, but I thought all that gives me is the chance to hear Sykes and Tyson duke it out. I look forward to that, but my expectation is of more heat than light to be honest.

Are we able to participate in the conference as a whole, then? I have registered, but I thought all that gives me is the chance to hear Sykes and Tyson duke it out. I look forward to that, but my expectation is of more heat than light to be honest.

I believe all the invited talks will be posted as videos and the slide presentations from most or all of the talks at the entire meeting will also be posted. That said, I am not a meeting organizer and cannot vouch this is absolutely correct. As to Sykes/Tyson, I am hoping for a more scientific debate, but knowing both and considering both fiends for 20+ years, I will say I do expect some entertaining barbs too!

Since planetary science is a field and planetary scientists have a profession, I do not think we can or want to retire the term which planets.

That's actually a very powerful argument I haven't really heard before -- that the scientific definition of planet should correspond to "worlds that have geology," because that's what Planetary Scientists study. That means, though, that our Solar System has about thirty planets, since this includes our moon and about seventeen other moons on top of the magic eight and the four dwarves. (Or am I completely confused? You're the real Planetary Scientist here.) :-)

Sometimes it does seem that all the counterarguments to this definition really boil down to "but what will we tell the children?" A fair point could be made that the definition should serve scientists -- not school kids -- given that there are in fact scientists to whom it's useful.

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